Modern vehicle air conditioners must meet a multiplicity of requirements. Some of the requirements are contradictory. For example, small dimensions of the components with high flow-through of air, as well as good temperature distribution and control at low costs.
A solution for the requirement of high flow-through of air and a very good temperature distribution are known from DE 10 2007 014 835.8. There, a system with a heating heat exchanger with a cold air passage is described. This system makes it possible to achieve a direct and detachment-free flow with good temperature distribution into the various air outlets. The temperature is controlled by means of a slider element or a combination of slider elements and a turning flap centrally placed.
A disadvantage in use of a single slider element is the structural space required. The slider flap requires a pocket in the housing so that the asymmetry of the heating heat exchanger with a symmetric flap is compensated for.
Owing to the geometry of the system, and especially of the slider, the air flow is disadvantageously affected. In an intermediate setting of the slider, only a small part of the cross section is opened or closed. Due to this, the air flow continuously shifts within the individual cross sections. Optimized mixing and a specific air guidance are largely prevented thereby.
The combination of a slider element and turning flap centrally located has led first to an increased structural space required, and secondly the distance between the heating heat exchanger and the slider element in the intermediate settings is small. This has a disadvantageous effect on air guidance through the heating heat exchanger, and thereby on mixing. Owing to the two structurally different elements, with this technical solution, expensive coupling systems are necessary, through which cost disadvantages arise.
An additional technical solution for an optimal temperature control consists in using three turning flaps, with one each placed before the heating heat exchanger elements as well as one before the cold-air passage. By this means the temperature is very well controlled, though with considerable structural space needed and design expense owing to the flap couplings. What is additionally disadvantageous is that in the individual end settings like “coldest” at which the air flows only through the cold-air passage, or “warmest” at which the air only flows through the two heating heat exchanger elements, the flaps guiding the air flow are positioned in the air flow. Owing to this, there is an increased flow resistance, also called system counterpressure, which can have a negative effect on the acoustics of the system.
From DE 698 20 990 T2, a flap actuator device for the air conditioner of a motor vehicle is known, which divides the air flow into two streams, and is driven via a toothed wheel and a toothed wheelwork on the flap corresponding to the toothed wheel.
What is disadvantageous with this configuration is that the air flow can only be divided into two streams, and that the system counterpressure is relatively high. Added to this is that the requirements for a temperature-layered flow of modern air conditioners are not met.